Production of zinc-dust.



Patented Mar. ll, I902. G. G. CONVERS &. A. B. DE SAULLES.

PRODUCTION OF ZINC DUST.

(Application fil ed Sept. 14, 1598;, I

4 Sheets-$heei l.

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V Patented Mar. II, I902. G. G. CONVERS & A. B. DE SAULLES.

PRODUCTION OF ZINC DUST.

filed Sept. 14, 1898.)

(Application 4 Shgets-$heeit 2.

(No Model.)

A 3 i: a a .5 1 l No. 695,376. Patented Mar. H, IQU Z.

G. CUNVERS & A. B. DE SAULLES. PRODUCTION OF ZINC DUST.

(Application filed Sept. 14, 1898.) (No Model.) 4'sheets sheefl 3.

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GEORGE G. CONVERS AND ARTHUR 13. DE SAULLES, OF SOUTH BETHLEHEM,

PENNSYLVANIA.

PRODUCTION OF ZINC DUST.

SPECIFICATION forming part of Letters Patent No. 695,376, dated March 11, 1902.

Application filed September 14,1898. $erial No. 690,911. (No specimens.)

To all whom, it may concern:

Be it known that we, GEORGE G. CONVERS and ARTHUR B. DE SAULLnseitizens of the United States, residing in South Bethlehem,

in the county of Northampton and State of Pennsylvania, have invented certain new and useful Improvements in the Production of Zinc-Dust; and we do hereby declare the following to be a full, clear, and exact descrip- IO tion of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Our invention relates to the production from zinc-bearing material of metallic zinc in t5 the finely divided or granular condition, known as zinc-dust or blue powder. Heretofore, so far as we are aware, this product has been obtained in relatively limited quantities as an auxiliary product in the metallurgy of zinc, whereas the purpose of our invention is to recover substantially the entire zinc component of the retort charge as zinc-dust.

The salient or main characteristic feature of our improvement depends uponthe discovery that the zinc-vapors in order to be precipitated in their entirety as zinc-dust should pass at once into a collecting-chamber sufficiently ample to receive them all, care being taken that the pipe or connection through which the vapors are discharged into the collector shall be above the distilling-point of the metal. At the beginning of the operation, when the retort contains a quantity of 3 5 air, and toward the end of the operation,when

the retort-charge becomes lean in zinc, more or less zinc oxid is produced, which oXid is taken off separately, so that it may not mix with the zinc-dust.

In the accompanying drawings, Figure 1 represents, partly in section and partly in elevation, a portion of a furnace suitable for the practice of our invention; Fig. 2 represents a cross-sectional view with one of the collectors in place. Fig. 3 represents said collector in front elevation and on a somewhat larger scale. Fig. a represents a crosssectional View of the collector. Fig. 5 represents a rear elevation thereof. Fig. 6 repre- 5o sents a top plan view of the collector-cover.

Fig. 7 represents a side elevation thereof.

Fig. 8 represents, partlyin section andpartly in elevation, another form of furnace suitable for the practice of our invention. Fig. 9 represents a vertical sectionalview thereof.

Similar letters of reference indicate similar parts throughout the several views.

Referring to the first form of apparatus, (illustrated in Figs. 1 to 7, inclusive,) A indicates the basal port-ion of the furnace, hav- 6o ing the fuel-chamber a, grate-bars b, ash-pit c, and bridge-wall d, overwhich the products of combustion pass to the downtake chimneyfiue e, as will be readily understood. Upon the side walls of the fuel-chamber rest the open-ended cannon f, and above them are located the zine-distillin g retorts n, the function of the cannon being to distribute the products of combustion about the sides of the retorts and to prevent the retort-bottoms from being subjected to too high a heat. The retorts n, as shown, rest upon refractory tiles or bricks built up from the base A of the furnace. Above the retort-chamber is provided with the arch B, and the entire furnace is strengthened and bonded by buck-stays and cross-ties, as shown. The retortsn have each an exit-opening m for the zinc-vapors and are charged from the opposite end, which is shown in Fig. 2 as lutedv up. The correspond- 8o ing wall of the furnace is removable in order to obtain access to the retorts and cannons. Adjacent to the vapor-exit ends of the retorts are arranged the collectors C for the recovery of zinc-dust. As indicated in Figs. 2 to 7, these collectors are preferably of general cylindrical form, flattened at the sides adjacent to the furnace, and provided with an opening 2%,which registers with the retort-opening 'm, the shortest possible pipe connection or nipple 'v uniting the two openings. The sheet-metal collector is strengthened by a dished bottom to and is closed at top by aremovable slip cover m, adapted, it need be, to receive a quantity of water, so as to regulate the effect, and serving also as a safety-valve should undue pressure develop in the collec tor. At its lower portion it is provided with a door or slide .2', covering an opening for the removal of the zinc-dust, and at a point op- 10c posite the retort it is provided with a door or slide .2, having, as shown, a sight-opening e through'which the interior of the collector may be observed. When disconnected from the retort, the collector may conveniently be manipulated by means of handles m. When in position, it may rest upon any suitable base-as, forinstance, the support 20. The retorts or muffles are charged with thezincbearin g material from the rear end-21 e. ,from the end opposite to that at which the collectors are located. At the outset a small sheetiron cone (indicated in dotted lines in Fig. 2

is attached to the retort-nipple for the purpose of catching the'oxid of zinc that is given offat the beginning of the operation. As soon as the color of the deposit at the outer end of the sheet-iron cone indicates the formation of zinc-dust the cone is removed, and slide a" is closed. The distillation is then continued until the fumes escaping at a small hole a (see Fig. 3) near the top of the collector begin to show again the presence of oxid of zinc. The sheet-iron cone or prolong is thereupon again placed in communication with the retort-nipple, so to catch, as in the first instance, the oxid of zinc that is being formed,therebypreventingitsadmixturewith the zinc-dust already collected. The rear end of the retort or muflieis then opened, the spent charge is withdrawn, and the muflie is freshly charged. The operation is then re-. peated, although, in general, the zinc-dust from each charge is removed from the collector before the fresh charge begins to distil.

. In so far as the temperature prevailing in the collecting-chamberis concerned we would say that in an ordinary run ofeight hoursduration the temperature for about four hours of that period at the region adjacent to the door 2, is somewhat above the melting-point of zinc (775 Fahrenheit) and thereafter somewhat above the melting-point of lead, (612 Fahrenheit,)although not so high as the melting-pointof zinc. During the first four hours the temperature at the upper part of the collector is above the melting-point of lead and below the melting-point of zinc and thereafter somewhat below the melting-point of lead. At the bottom of the collector the temperature during the entire operation is somewhat below the melting-point of lead,although still comparatively high. The size of the collector will depend upon the richness of the charge and the corresponding volume of the zinc-vapors. a condenser four feet high and two feet in diameter will collect two hundred and sixty pounds of zinc-dust in twenty-four hours.

In the apparatus shown in Figs. 8 and 9 the retorts or muffles n are multiplied and are arranged in vertical series, so as to give greater capacity of output, each double vertical series communicating through the openings m directly with a collecting-chamber 0, provided with slides a and 2 corresponding in function to the slides z and z of the collector C. At its top each collector C is provided with an opening closed by a slip cover or lid In practice, we have found that m serving as a safety-valve, said cover having a small aperture n of about one inch in diameter for the same purpose as the like aperture 5 of the collector O. The furnace is stayed and bonded, as shown, and is provided with the fuel-chamber a, grate-bars b, ashpit c, arch B, and chimney-stack D, as will be readily understood. The mode of operation of this modification of the invention'corresponds to that hereinbefore described, the recovery of the zinc-dust taking place in the collectors C. The prolongs, (one of which is indicated in dotted lines in Fig. 9,) as before, are adjusted to the muffle-openings m at the outset and toward the end of the operation, so as to catch the oxid-of-zinc vapors developed at those periods, but are of course removed dnring the period of deposition of the zinc-dust in the collectors. The construction has the advantage of dispensing entirely with the'intermediate nipple o of the collector 0, thereby absolutely insuring against the possibility of the formation of melted zinc at that point. Moreover, it enables one collector to be used for muflies located one above the other, a matter of difficulty if a single sheetiron collector were employed, because of the fact that in adjusting such sheet-iron collector to the several muffles it is found in practice that it is almost impossible to make the various nipples register exactly with the corresponding openings in the casing and make reliable gas-tight joints.

The recovery of zinc-dust as a by-product in the manufacture of zinc has been heretofore practiced; but the amount thus obtained has borne but a slight ratio to the furnace charge. Our invention, on the contrary, is designed to recover in the form of zinc-dust substantially the entire body of distilled zinc given off from the mufties, a result which has heretofore, so far as we are aware, never been attained or even approximated. The zincvapors immediately upon their issuance from the muffle are expanded in the collector while still at the temperature of volatilization and without having an opportunity to liquefy pass at once and in their entiretyinto the dust or granular condition, the product at the prevailing market rates being very much more Valuable than either bar-zinc or zinc oxid.

Having thus described our invention, whatwe claim is 1. The process of obtaining the substantially maximum yield of zinc-dust or blue powder from a given retort charge,which con sists in preliminarily heating the charge toeifect the distillation of the zinc, receiving the metallic-zinc vapors given off from the charge, in their substantial entirety fromthe muffle directly into a collecting-chamber, thereby maintaining their temperaturethroughout above the point of liquefactionof any substantial portion of the vapor until they have entered the collecting-chamber, and immediately condensing them in said chamber under such conditions of temperature and IIO expansion as will precipitate them in substantially their entirety in the form of zincdust, substantially as described and for the purposes set forth.

2. The process of obtaining the substantially maximum yield of zinc-dust or blue powder from a given retort charge, while excluding injurious admixture of zinc oxid therewith, which consists in preliminarily heating the charge to effect the distillation of the zinc, conveying off separately the preliminary oxid-of-zinc vapors generated in the retort, then receivingthe metallic-zinc vapors given off from the charge, in their substantial entirety from the muffle directly into a collecting-chamber, thereby maintaining their temperature throughout above the point of liquefaction of any substantial portion of the vapor until they have entered the collecting-chamber, and immediately expanding and condensing them to zine-dust in said chamber; substantially as described and for the purposes set forth.

3. The process of obtaining the substaniially maximum yield of zinc-dust or blue powder from a given retort charge, while exeluding injurious admixture of zinc oxid therewith, which consists in preliminarily heating the charge to eifect the distillation of the zinc, conveying oit separately the preliminary oxid-of-zinc vapors generated in the retort, then receiving the metallic-zinc vapors given off from the charge, in their substantial entirety from the mufiie directly into a collecting-chamber, thereby maintaining their temperature throughout above the point of liquefaction of any substantial portion of the vapor until they have entered the collecting-chamber, immediately expanding and condensing them to zinc-dust in said chamber; and interrupting the flow into the col lecting-chamber when, at the final stage of the operation, oxid-of-zinc vapors reappear therein; substantially as described.

In testimony whereof we affix our signa tures in presence of two witnesses.

GEORGE G. GONVERS. ARTHUR B. SAULLES,

Witnesses:

OSWIN W. SHELLY, EDWARD J. MALLOY. 

